Surface NMR within a geophysical study of an aquifer at Haldensleben (Germany)

The surface nuclear magnetic resonance (SNMR) method has been tested at a s ite in Haldensleben, northern Germany, to assess the suitability of this ne w method for groundwater exploration and environmental investigations. More information is obtained by SNMR, particularly with respect to aquifer para meters, than with other geophysical techniques. SNMR measurements were carr ied out at three borehole locations, together with 2D and 1D direct current geoelectrics, as well as ground-penetrating radar, and well logging (induc tion log, gamma-ray log and pulsed neutron-gamma log). Permeabilities were calculated from the grain-size distributions of core material determined in the laboratory. It is demonstrated that the SNMR method is able to detect groundwater and the results are in good agreement with other geophysical an d hydrogeological data. Using the SNMR method, the water content of the uns aturated and saturated zones (i.e. porosity of an aquifer) can be reliably determined. This information and resistivity data permit in situ determinat ion of other aquifer parameters. Comparison of the SNMR results with boreho le data clearly shows that the water content determined by SNMR is the free or mobile water in the pores. The permeabilities estimated from the SNMR d ecay times are similar to those derived from sieve analysis of core materia l. Thus, the combination of SNMR with geoelectric methods promises to be a powerful tool for studying aquifer properties.